Plural channel signaling



June 21 1927.

R. A. HEISING PLURAL CHANNEL SIGNLING Filed March 5, `1916 l loo@ KQ.

rasees Jue@ ai, 1927.

innate unirse stares Parser clerics.

RAYMON D Ai EEISING, OF EAST GRAN GE, NEW JERSEY, ASSIG-NOB TO WESTERN ELEC- TRIO COMPANY, INCORPORATED, OF NEW YORK, N. Y., A. CORPORATION OF NEW ILURAL CHNNEL SIG'NALING. i

Application led Merch 8, 1816. Serial No. 81,980.

y This invention relates toa method of and ineans for lural channel signaling with modulated higliifrequencyiwaves. Its object is'torovide improved methods and a paratus or carrying into effect the methodjs of 'transmission and reception of several independent messages.

In'radio signaling by means of high frequency Waves, it would be possible to send several messages by radiating simultaneously several high frequency Waves, modulating each one and receiving bynieans of circuits tuned to each Wave, but in practice the numbcr of Waves which can be so sent is limited by the tendency toward interference at the receiver, unless the frequency interval be tween any two Waves is rather large.

The present invention provides means whereby any one of these non-interfering radiated Waves-may itself carry several independent messages and whereby the total number of messa ges,which may be transmitted Without interference at the receiver, is increased. This object is accomplished by modulating one of the waves radiated, say one whose frequency is a million, by means ot another wave whose fre uency is lower, but above the limit of audibility and constant, torexample 50,000'cycles per second, andby modulating this second wave in accordance with a signal to be sent. At the saine time the radiated wave of frequencyv one million maybe modulated by several other such secondary waves, orexample,

waves of frequencies 40,000-30,00020,000,

each of these secondary waves being modulated in accordance with one of a number of independent signals. In the particular case above, four signalsmay therefore be sent by means of the same carrier wave of the con stant frequency one million. By using several other non-interfering carrier waves, for example three, a total of sixteen independent messages may be 'sent as against but four it the. secondary modulating waves were not employed. Thisv may be accomplished with the same frequency interval between radi ated waves in the two cases.

The method of carrying out this invention will be described more in detailin connec tion with the drawings, in which Fi re 1 representen transmitting station and-uFigfrequency,

-ure 2 a. receiving station constructed in accordance with this invention.

-lReerring to Figure 1,1 represents a generator of waves of high frequency, for example one million cycles per second and 2 is a circuit energized by the generator 1 and connected to the input terminals of athermionic amplifier 3 is' a generator of waves of lower frequency, perhaps 40,000 cycles per second, and 3', 3, etc. are other generators of different high frequencies, all less than that of the generator 1. t is a. tliermionic amplifier, Whose input circuit is coupled to the circuit of generator 3 and also to a circuit 5, which contains a microphone or other primary source of low fre quency signal currents. Similarly 5 and 5" represent other independent sources of signals to be transmitted simultaneously. The output circuit of the amplifier 4. is connected yt0 aicirmittunedntmtbs fqllency gener" ated bykwhich in turn is modulated currents of the frequency generated by 8 appear in the circuits 5 and are superposed upon the currents appearing in the circuit 2. There are, therefore, impressed upon the input circuit of amplifier 7-first, waves of frequency generated by l and second, a series of waves of frequencies determined by 3, 3', etc., which latter waves are modulated in accordance with the primary sources of signals. There will, therefore, appear in the output circuit of amplifier 7 and in the circuit 8, tuned to the highest a high frequency wave modulated in accordance with a series of modu lated high fre uency waves. The amplifiers 9 are arrange to increase the intensity of this modulated Wave and impress it upon the radiating antenna 10. f

Referring to Figure 2, 12 represents a receiving antenna lwhich is coupled to the 'circuit 13 tuned to the frequency generated by the generator 1 of Figure 1. 14 is a detector whose `in ut circuit is connected across the tuned circuit 13 and in whose out put circuit will appear a current Whose amplitude is the enve ope of the radiated high frequency Wave. The circuit 15 is tuned to the frequency of the generator 3 of Figure 1, 15 to the frequency of generator 3', etc.

mi coupled tothe circuitQ. By means of this arrangementquency current originating in generator 3.l

The detector 17 whose input circuit is connec'ted across the tuned circuit 16 serves to detect the incoming signals from that circuit and to impress an audible signal upon the Atelephone receiver 18. Similar detecting circuits (not illustrated) are connected to the tuned circuits 16,'16, etc. i'

The detection b detector 14 thus eliminates the effect o the high frequency carrier Wave and allows the lower fre uency signal-modulated waves to be selected y thev tuned circuits, and the lower frequency signal-modulated waves, by detector 17, then.

produce in each telephone receiver a current which is the envelope of the intermediate waves, and consequently audible.

It will beclear that by this arrangement four independent signals may be transmitted on but one high frequency radiating wave. For sim licity only one high frequency generator, orexample of waves of n 'million cycles er second, has been illustrated, but it is obvious that other radiating frequencies may be employed to increase the number of signals which may be transmitted.

Inthis method' 't is, of course, essential that the frequencies generated by the generators 3, 3', etc. ,shall be above the limit` of audibility and that the frequency interval between successive waves shall be suicient to prevent interference. A. characteristic feature of this system and method is successive modulation at a transmitting station. Another characteristic feature is successive detection at a receiving station.

It will be clear that this invention need not be restricted to radio signaling, but may be applied equally Well to other selective systems or to systems operated by means of carrier waves over Wire conductors. It may of course be used in a system in -which several stations generate simultaneously-the same lhigh frequenc but in which these waves are modulate by different intermedil ate waves. In that case no interference will be produced between separate stations, even though each is radiating the same fre uency wave when modulation is not taking p ace. What is claimed is: v i

1. A system com rising means for produc-V,

ing a uniform hig frequency wave, means for producing a plurality of independent periodic energies each of periodicity above for producing, a plurality 'of independent periodic energies atleast one of which is of periodicity above the usually employed range of audible sound wave frequencies, and means controlled bythe Wave' supplied by s a'id first named means for producing another Wave and controlled by said energies for causing it to simultaneously undergo a plurality of variations in accordance with said plurality of energies.

' 4. The method which, comprises modulat ing a given wave by a wave .of lower frequency a'ndemploying a product of the first modulation to modulate a Wave of higher frequency than the given Wave, all at the sa'me station, transmitting 4.the resultant energy and deriving signals therefrom by successive detection.

5. The method which comprises successively repeating waves in transit through a channel of transmission, and successively modulating Waves during transmission through said channel, all at the same station. v

6. The methodof signaling which comprises roducing two different Waves ata transmitting station, modulat-in one of said waves in accordance with a signa and modulatingA the other of said Waves in accordance with said modulated Wave.

7. .The method'which com rises generating a uniform ca'rrier wave, an modifying said -carrier wave to transmit elements of a plurality of telephone conversations thereon simultaneously.

8. The method which comprises generating a uniform and continuously maintained carrier .wave,. modifying said, continuous wave to transmit a plurality of messages simultaneously, said messages including a telephone message, and causing certain portions of said wave to carry portions of a plurality of the messages.

9. The method which comprises generating an unmodified carrier wave, segregating the Aenergy of sa-id unmodified wave in a circuit,

' in accordance with taneou'sly.

with ai pimiay ef the wave trains Sismi- 11. A system comprising upon said;circuit. 19.. A' method of obtaining Vmodulated Wavesof large energy for Signaling purposes which consists-in 'producing af low-frequency Wave, a high frequency wave and' a higher' vfrequency wave cach independently of the other, causing the modulation' of the wave of high frequency by-th'e inw-frequency Wave,

producing modulation of the wave of frequency higher than that of either of the lirst two-mentioned waves by the modulated' vvave, and amplifying thehighirequency producing and segregating into separate circuits waves corresponding to each of said "pluralityof other waves, and means for de- .tecting each of said other waves.

modulatedwav'e all at the same-station; 13 The method of signalingwhic'lrcomrises simultaneously modulating a high iiequency Wave by other waves of'loW-f said other waves each being plurality 'of modulators each having input frequency modulated in accordance with signals.

14. The method of signaling which comprises modulating vhigh frequency Wavesby means of signal waves, employing said modulated waves to simultaneously modulate other waves of high fr uency, and successively' detecting said modu ated other Wavesat a re-l ceiving station. i

15. A system comprising a source of high. 5

frequency Waves,- a pluralit o f sources o other waves, ya modulating eviceenergizedby said `first na'med source, and individual channels of unsymmetrical vvave transfer characteristic, one for each of said plurality of sources, for conveying waves to said device vfrom said pluralityof'so'urces' whereby said plurality of sources are substantially prevented from reacting on eachother, means for transmitting Waves from said modulating device, means for receiving transmitted Waves, and means for causing-the selective operation of aj plurality of instruments each Waves from a particular one oftsaid sources. 16. Themthod comprising -inodulatinlg a carrier wave in accordance witha plura ity of different frequency currents, transmitt' and receiving the energy of 4said modulate carrier wave, detecting said received energyV to produce a complex current including as components waves having the frequencies of said currents, and causing each of said waves to selectively operate a device .individual thereto .at a receiving station.

17. The method of comprising modulating a wave in' accordance with signals at one station, modulating at the same station a' second wave in accordance with said modulated wave, radiatingv said modulated second wave, receiving said raradio transmission diated wave and successively detecting said wave'to reproduce said signals. an electrical channel of transmission having modulatorsin tandem at the same station, each modulator comprising a` discharge device having a circuit for controlling the discharge and means for impressing the Waves toi be .modi'i'late'd- -l charge device which comprises simultane- 'ously impressing upon the electron dis- -cliarge device different frequency currents,

and I :nreveiiting the currents from one path from traversing another path in a direction toward the source associated with said other path, `'whereby interference of one of said sources with the operation of the others is prevented.

-j-19. A' signaling system comprising means Afor'producing a carrier wave, a single modulating instrumentality for simultaneously modulating said carrier wave in accordance witha plurality of other waves, means-or &

20. A system comprising at one station a and output circuits, the output circuit of one of said modulators' being adaptedto supply vvaves to the input circuit of another of said modulators, and means for utilizing waves supplied .byv one of the modulators which are of. a frequency different from those, supplied to the input circuit thereof.

2l. AA selective system comprising. atone stationa plurality of vacuum, tube modulators of electrical waves, the outputA circuit of one ofsaid modulators 'being connected to the input circuit of another of said modula- 22. A'system comprising means for successively modulating several electrical waves each, except that of the lowest requencyjn accordance withA Waves of lower frequency,

Ain combination-with a plurality of Wave distortiiig devices connected Ain tandem forderiving .from the successively .modulated wavesother Waveshaving the frcquenciesqf rier frequenlcy5 a second audion detector :ada ted to befsupplied with energy from `sai first-mentioned detector, a' circuit vfor connecting said detectors, said connecting circuit -comprising means for tuning the same .to a carrier frequency different from saidrstv mentioned carrier frequency,'and

-- a 'signalingdevice associated with said detectors.

24. A signaling system comprising at one 'station means including a space discharge device having an anode, a cat ode and space im dance controlling means for producing a signal modulated wave, and means includsystem comprising 'an ing a space discharge device having an anode, a cathode and space impedance controlling means for modulating another wave in accordance with elements of said signal modulated wave. L

25. The combination at one station of two modulators of electrical waves in tandem in anA electric wave transmission channel, each of said modulators comprising an electron discharge device having a cathode, an anode and a control element.

26. A plurality of modulators, signaling means and a source of carrier Waves associated with each of said modulators, and an additional source of carrier waves and a modulator in common to said plurality of modulators.`

27. A. signaling systemiincludinglmeans for producing high fre uency currents in a circuit, means for modu ating said currents in accordancewith otherv currents, means for modulating said other currents in accordance with signals, and a receiving station comprising tuned' circuits for separating said frequency components and detecting devices responsive thereto. Y

28. In ay transmitting system, electrical energy supply means for setting up at one st ation a plurality of unidirectional currents, means for varying one of said currents in accordance-with a signal wave, means for varying a second. of said currents in accordance y'with a mode of'variation in the first which is-different from the mode of variation of said signal wave, and means for varying a third of said currents in accordance with a mode of vvariation in the second.

29. In a systemfor energy transmission, a station comprising a Wave source, means for varying the characteristics .of the wave produced by said source .in accordance with an electrical variation current, means for producing another wave, and additional `means for varying the characteristics of said other wave in accordance with said varied wave. y 4

30. In combination, asingle detector controlledby high frequencywaves to produce a complex current, means to derive from said complex current*- individual wavescorresponding to different messages, circuits into which-said individual waves are respectively segregated, and4 means at least partly including said aforementioned means to prevent said circuits from reacting upon each other. l

31'.` In a system for transmitting energy, a station comprising means forsuccessively modulatingl a plurality of waves in ac: cordance .with variations representing'the saine signal elements, and sources of energizing current other than said Waves for supplying each of said means for modulating.

32. A transmitting station comprising J n), I

sources of a plurality of waves of different waves in accordance with said modulated wave. 'i

34. A signaling system comprising at one station vmeans including a space discharge device having an anode, a cathode, and space impedance controlling means for varying a wave in accordance' with a signal, and means including a space discharge device having an anode, a cathode, and space iin edance controllingl means for varying anot erwave by at least one component of said varied wave, and a selective circuit connected in tandem between said devices.

35. A signaling system comprising a unitary means functioning in common to a plurality of message transmitting channels for generating a carrier wave; means for simultaneously transmitting a plurality of messages, including a telephone message, on the carrier wave produced by said unitary means.

36. In combination, a single detector operating on high frequency waves to produce a complex current, selecting means to derive from said complex current individual currents corresponding to different messages, and individual detectorscontrolled by the individual currents. v' 37. In a signaling system, means for generating a high frequency carrier wave at a station, means for generating an intermediate frequency current at the same sta-v tion, means for roducing a signal current, means for modu ating the intermediate frequency current b the signal current, means for modulating the high frequency, wave by the modulated intermediate frequency current, and. means tending to prevent the modulation of the highI frequency wave by tlie signal current.

38. The method which comprises generating a high frequency current, generating an intermediate frequency current, producing a signal current, modulating the intermediate fre uency current by the signal current at a station, modulating the high frequency current by the modulated intermediate frequency current at the same station, and preventing the modulation of the high frequency current by the signal current.

i'en

39. The method of transmitting energy l isb 1,css,1oo 5 the intensity of that energy having the next lower frequency, and preventing its variation in accordance witli'variations in intensity of an energy of still lovver frequency.

40. A signaling system comprising means for modulatinghigh frequency-Waves in accordance with signal Waves, means for cansing said modulatedwaves to modulate other waves of high frequency, Ameans for t-ransmitting energy. of said other waves, and a receiving station-including means forysuccessively detecting said transmitted waves.

41. A system comprising a carrier wave source, a circuit connected to said'sourcein which unmodulated Waves'producedgg?I said source are segregated, means -for pr ucing acarrier waves-controlled by energy'in said circuit and modulated in accordance with aA plurality .of lower vfrequency waves, means for transmitting energy controlled bysaid modulated carrier wave, a distant station for receivingsaid transmitted energy, and a plurality of devices at said receiving station' -each adapted to lbe actuatedjin accordancev cuit, a detector arranged to be controlled byv said closed circuit, a circuit including a source of electric energy arranged'to be controlled by said detectcr,ajplurality of sec-v,

ondary closed circuits arranged to be controlleds'by said second nientioned'closed cirl cuit and tuned to respond to differentv secondary frequenciesres ectively, a plurality cuits res ct'ively, and a plurali of devices arrange to be separately 4contro led by said last mentioned detectors respectively."

44. The method of transmission which comprises sending from the transmitting station a high'frequency wave modulated in accordance with a plurality of modulated high frequency'waves. Y

45. The method of impressing-'upon ,a transmitting medium electrical energy rep# `re'senting speech, which consists generating at one station electric currents ofv dfof detectors controlled y said secondary cir-.

46. Transmjtting apparatus comprisin means for producing electric currents of di ferent inaudible frequencies interacting to produce beats,`means for controlling the en ergy at the same station where it is prol duced to represent a signal or message, means for amplifying the beat energy, a transmitting medium, and means for impressing the amplified beat 'energy upon said transmittin medium.

4%; Transmitting apparatus comprising means at one radio terminal station for roducing electric currents of different inau 'ble frequencies interact-ingl to produce beats cf inaudible frequency, means at said station k'for controlling the energy to represent a signal orfmessage,fa transmitting medium,V

means for amplifying-.the beat energy before transmission, and means for impressing the am lied beat energyupon said ,transmitting me ium. ..48.1In'a Wave receiving system, the combination, at Aone station, of a receiving con.

ductor a dischar e device having a cathodecontrolfelement circuit coupled to said conductor for the reception of ener therefrom,

Aan anode-cathode circuit for sai device, a se-v lective circuit coupled to the anodecathode circuit 'for selecting ,waves of a 'frequency other than the Wavesl transferred fromy said receiving conductor, and aA device operated by energyof the selected Wave frequency to produce waves .of other frequency.

49. In a wave receiving system, a conduc tive interceptor of wave energy included in a tuned circuit,'a circuit including the grid and cathode fofj anelec'troi'i discharge device coupled to. said tuned circuit,. a-plate or 'anodeto-'cathode .circuit for said device including a high frequency coil' and a source "of electric current, for example, a battery,

a selective circuit includingv acoil connected to said first/mentioned coil, said selective circuitbeingfsel'ective v.of a fre uenc other than that toJ'which the circuit mclu ing the interceptoi'f is tuned, sifiidcircuit being electrically gconnected inenergy transfer Vrelation to the cathode and'control element of a second electron discharge device, and a .plate or anode circuit for said second elec--AV tron discharge device for transferring electrical energy to an indicating instrument.

so. The method of radio1 teiephon which consists in impressing telephonic'vi rations representing different conversations upon a ferent inaudible frequencies interacting tol roduce beats of inaudible frequency, moduating'at the same station the energy in ac cordance with speech, amplifying the beat energy,l and impressing the amplied energy upon the transmitting medium.

Qual to lone vplurality of .electric wave group frequenc variations, each conversation being`-indivi roup frequency variation, impressing sai tions thus modified by speech upon another wave group frequency variaelectric wave, controlling -theproduction in an antenna of a Wave having essentially the 4wave form of the lother 'electric wave thus modified, and receiving signals by impressing the. radiant energy upon circuits tuned to wave length and group variation cies. n

51. A receiving system for waves comprising successively responsive circuits connected together in cascade relation and tuned, respectively, to different frequencies above Good audibility, a wave amplifyin relay interposed between said circuits, an a device arranged to be actuated in response to the conjoint action of said circuits.

52. The method of radio signalin which consists in translating a plura 'ty of ow frequency signaling currents into higher frequency currents which are lower than radio requencies and which are different 1n frequency from each other, and conjomtly 1ncreasin each of said frequencies bytranslating t emto still higher frequencies, so as to step them up into a range suitable for radio transmission. v

53. In a radio system, a plurality of low frequency signaling circuits, modulators associate'd with said circuits for' modulat1ng separate carrier frequencies in accordance with low frequency signals transmitted over said circuits,'a common modulator, means frequenvwhereby -the resultant modulated frequen- -cies may be im ressed Aupon said common modulatorgthere y modulating another frequency .and producing -thereby a band of radio frequencies. A Y

54. A signaling system comprising a modulator having an input circuit and an output circuit, means for supplying carrier waves to said Inodulator, a plurality of messa e channels associated with said input circuit, eachof said channels comprising means for 'discriminating against currents from the other channels, and a transmission circuit associated with said output circuit.

. 55. In a signaling system, the combination l.of an electron discharge device, a plurality of input circuits adapted to impress a'plurality of currents simultaneously upon said device, and means connected in each input circuit to protect the respective input circuits from interference by currents of the A frequencies impressed upon the other input circuits.

56. In a high frequency signaling system, tle combination of'a modulating device, a circuit supplied by source of current of one frequency, a' circuit supplied by source of `current of different frequency, each of said circuits having selecting electrical networks adaptedto transmit currents of the frequency produced by each'particular source, and each of said' circuits being so connected with its supplying source as to prevent current in one of-said' sources inducing currentA in the other of said sources.

57. A system for transmitting and receiving radiant energy, co'mprisirfifgv means for emitting a series of radiant impulses having a frequency substantially aboye audibility,

and means for impressing upon said im pulses a series of periodic variations having a frequency different from the said first mentioned frequency and substantially above audibility, in combination withmeans for receiving said impulses and variations including two elements tuned to respond selectively to said impulses and variations respectively, a vacuum tube rectifier interposed between said elements, and a receiving device arranged .to be controlled by the conjoint action y,of said elements.

- 58. lA system for transmitting and receiving radiant energy, comprising means for emitting a series of radiant impulses having a frequency substantially above audibility, and means for impressing upon said impulsesa series of periodic variations having a uency different from the said rst mentioned frequency and'substantially above audibility, in combination with means for receiving said impulses and variations including two elements tuned to respond selectively to said impulses and variations respectively, a vacuum tube rectifier interposed between said elements, and a receiving device arranged to be controlled b the conjoint and successive action of sai elements.

59. A system of wave transmission comprising .at one station a source of waves, a

wave modifying device controlled by a sig naling device for effecting signaling variations in said waves, a selective circuit for transmitting selected waves from said wave modifying device to a second wave modifying device, additional means for supplying other waves to said second wave modifying device,.and an outgoing transmission conductor supplied with waves from said second wave modifying device.

60. In a System inaccordance with claim 59, a second selective circuit connected between said second wave modifying device and said transmission conductor and selective of' waves 'of adi'erent frequency range than said first named selective circuit.

61. A system for the reception of speech modulated or modified carrier waves comrising at a receiving station a first detector, or example, a rectifier, upon which the received waves are impressed, anda circuit for supplying from said detector to a second detector, for example, a rectifier, waves pro duced b said first detector, anda circuit designe to freely convey speech waves and containing a speech reproducing instrument supplied by said second detector.

62. The method of receiving speech modi. fied high frequency waves and derivingl speech currents therefrom which comprises detecting the high frequency waves to pro- /duce currents, selecting from the resultant currents other high frequency currents, and detecting the selected currents to reproduce the speech currents,

lao

63 A system for carrier wave transmission and reception comprising a transmitter including elements for impressing speech Wave variations on high frequency waves,

- and a receiver comprising at one station two detectors, one of which is supplied by waves incoming from said transmitter, the second of which issupplied by waves from said first detector, `and a circuit supplying al speech -reproducing instrument with waves supplied 10 from said second detector whereby variations corresponding to the speech wave variations impressed upon the high frequency waves are reproduced asspeech.

In Witness whereof, I` hereunto subscribe 15 

